The objective of this research is to increase the understanding of subunit interactions in self-associating systems. Kinetic studies provide the capability of probing the mechanism by which aggregates form, enhancing the knowledge of regulatory aspects of these structures, as well as aiding in the description of the molecular events producing such effects. In particular, work will be directed to delineate the roles of electrostatic and hydrophobic interactions in the isodesmic self-association of glutamate dehydrogenase through the sensitivity of the kinetics to variations of pH, ionic strength, and temperature. Similar studies will be performed on the highly cooperative condensation polymerizations displayed by deoxy hemoglobin S and tubulin. In contrast to glutamate dehydrogenase, the mechanism of assembly is not as well understood and particular attention will be paid to defining it. These kinetic experiments will be performed in a pressure relaxation instrument recently constructed in this laboratory, using scattered light to monitor changes in molecular weight induced by the pressure perturbation. Ancillary equilibrium measurements will be performed by analytical gel chromatography at ambient pressure and by spectroscopic measurements at elevated pressure in a specially constructed cell.